This invention generally relates to camera-based obstacle avoidance systems for vehicles. In particular, this invention relates to an improved structure for a combined backup camera and driver alertness system for a vehicle.
When a vehicle is traveling in a reverse direction, the potential exists for collisions with both stationary and moving objects such as fire hydrants, guardrails, other vehicles, pedestrians, bicycle riders, children, animals, etc. To reduce the potential for collisions, some vehicles are provided with obstacle avoidance systems that use rearwardly viewing camera that provide the vehicle operator enhanced ability to view objects at the rear of the vehicle. These camera-based obstacle avoidance systems display images from the camera on a display, allowing a driver of the vehicle to more easily see objects that might otherwise be hidden from his or her view. These camera-based obstacle avoidance systems can also include an image processor that supplements the images from the camera by highlighting objects that are calculated to be in the path of the vehicle and/or suggesting directions for evasive movement. Some of these camera-based obstacle avoidance systems can also generate a warning signal to the driver, such as an audio signal, when it has been calculated that the vehicle may be about to collide with an object in its path of movement. Other camera-based obstacle avoidance systems are known to automatically implement collision avoidance measures, such as applying the vehicle brakes, when a collision with an object is imminent.
Driver fatigue is also a known causes of accidents, particularly when the vehicle is traveling in a forward direction. To address this, a variety of devices are known that generate a warning signal when certain characteristics of driver fatigue have been sensed or calculated. One of such characteristics is the relationship of the vehicle to lane markers on the road, referred to as road lane drift. Road lane drift typically refers to the gradual movement of the vehicle from a centered position on a road lane (as determined by the lane markers on the road) laterally toward such lane markers. Driver alertness systems traditionally use a forward aimed detection device, such as a camera or other sensor, to monitor the position of the vehicle relative to lane markers on the road. These driver alertness systems include algorithms that use the images from the camera (specifically, the locations of the lane markers that are illustrated in such images) to calculate the path of the vehicle relative to the lane markers. If the vehicle is drifting, weaving, or otherwise moving relative to the lane markers in a manner that suggests driver fatigue is occurring, the driver alertness system can generate an audio, optical, or tactile warning to the driver.
As mentioned above, driver alertness systems typically use a forwardly directed camera. Externally mounted camera and other road monitoring devices can be affected by weather conditions, such as wet roads, rain, snow, etc. that can partially obstruct the view of the lane markers on the road. Additionally, road hazards (such as stones and other debris) also can damage external monitoring devices. For these reasons, the cameras of many driver alertness systems are mounted in a passenger compartment of the vehicle, frequently adjacent to a rear view mirror provided on a front windshield. However, in this location, the camera is located relatively far from the surface of the road and, consequently, must “look” at the road from over the vehicle hood. Consequently, the camera is blocked from capturing images from the portion of the road that is immediately in front of the vehicle, and the lane markers that are visible to the camera are generally ten feet or often more in front of the vehicle. In addition, when the camera is located within the passenger compartment of the vehicle, the front windshield may distort the images that are captured thereby. Thus, it would be desirable to provide an improved structure for a combined backup camera and driver alertness system for a vehicle that avoids the issues mentioned above.